This invention relates to novel halogen-containing organometallic compounds and their use as flame retardants.
Flammable macromolecular materials, e.g. thermoplastic formulations, can be rendered flame retardant by treatment with a combination of antimony or bismuth trioxide and a halogen-containing compound. The trioxides act as synergists and enable a reduction in the amount of halogen-containing compound needed to obtain the desired flame retardant effect. It is not fully understood how these trioxides operate to allow for this reduction, however, it is postulated that the antimony or bismuth trioxide react with the halogen provided by the halogen-containing compound to form antimony or bismuth trihalides or oxyhalides. A decomposition mechanism has been proposed in which these trihalides or oxyhalides decompose in a stepwise manner and thus participate directly in flame-quenching reactions.
Application or incorporation of the antimony or bismuth trioxide and the halogen-containing compound onto or into the macromolecular material is generally accomplished by coating, blending or mixing. Due to the fine particle size and toxicity of the trioxides, care must be taken during these procedures so as to not contaminate the workplace.
While industry has developed techniques to insure safe handling of these trioxides, these techniques add cost to the flame retarding of the macromolecular material. To avoid these costs, it would be desirable to have a flame retardant system which does not require the use of antimony or bismuth trioxide but which still maintains the presence of antimony or bismuth in the flame retardant system and thereby enjoys the benefits thereof.
To this end, therefore, it is an object of this invention to provide novel halogen-containing organometallic compounds which exhibit excellent flame retardancy without the presence of antimony or bismuth trioxide. It is also an object of this invention to provide novel halogen-containing organometallic compounds which have other uses, such as, polycondensation catalysts.